feat: introduce types.ftl.go to register sumtypes, which fixes enco…

…ding in unit tests (#1909)

Fixes #1577

This change introduces a new generated file `types.ftl.go` in the
user-defined package itself to make sure sumtype registrations get
called when running unit tests.

Notes:
* This change also includes a subpackage `subpackage` in the test data
that is not yet unit tested. Unit tests should be added (identical to
the parent package's unit tests) after
#1903 is resolved. Some work
will also need to be done to extend the `types.ftl.go` generation to
working on subpackages.
* This works by extending the existing logic operating on
`mainModuleContext`, which means that code now generates not only just
the literal `main` package, but also the conceptual _main_ package's
additional artifacts. I couldn't come up with a name that would be
better, so it's left as-is in this PR, but please let me know if you
think of something better.

backend/schema/encoding.go

@@ -34,6 +34,9 @@ func EncodeComments(comments []string) string {
 
 	w := &strings.Builder{}
 	for _, c := range comments {
+		if c == "Code generated by FTL. DO NOT EDIT." {
+			continue
+		}
 		space := ""
 		// Empty lines should not have a trailing space.
 		if c != "" {

common/moduleconfig/moduleconfig.go

@@ -227,7 +227,7 @@ func replacementWatches(moduleDir, deployDir string) ([]string, error) {
 
 // findReplacedImports finds Go files with imports that are specified in the replacements.
 func findReplacedImports(moduleDir, deployDir string, replacements map[string]string) ([]string, error) {
-	var libPaths []string
+	libPaths := make(map[string]bool)
 
 	err := filepath.WalkDir(moduleDir, func(path string, d os.DirEntry, err error) error {
 		if err != nil {
@@ -243,7 +243,7 @@ func findReplacedImports(moduleDir, deployDir string, replacements map[string]st
 				for oldPath, newPath := range replacements {
 					if strings.HasPrefix(imp, oldPath) {
 						resolvedPath := filepath.Join(newPath, strings.TrimPrefix(imp, oldPath))
-						libPaths = append(libPaths, resolvedPath)
+						libPaths[resolvedPath] = true
 						break // Only add the library path once for each import match
 					}
 				}
@@ -252,7 +252,26 @@ func findReplacedImports(moduleDir, deployDir string, replacements map[string]st
 		return nil
 	})
 
-	return libPaths, err
+	return deduplicateLibPaths(libPaths), err
+}
+
+func deduplicateLibPaths(libPaths map[string]bool) []string {
+	for maybeParentPath := range libPaths {
+		for path := range libPaths {
+			if maybeParentPath != path && strings.HasPrefix(path, maybeParentPath) {
+				libPaths[path] = false
+			}
+		}
+	}
+
+	paths := []string{}
+	for path, shouldReturn := range libPaths {
+		if shouldReturn {
+			paths = append(paths, path)
+		}
+	}
+
+	return paths
 }
 
 func parseImports(filePath string) ([]string, error) {

go-runtime/compile/build-template/types.ftl.go.tmpl

@@ -0,0 +1,17 @@
+// Code generated by FTL. DO NOT EDIT.
+package {{.Name}}
+{{if .LocalSumTypes }}
+import "github.com/TBD54566975/ftl/go-runtime/ftl/reflection"
+
+func init() {
+	reflection.Register(
+{{- range .LocalSumTypes}}
+		reflection.SumType[{{.Discriminator}}](
+			{{- range .Variants}}
+			*new({{.Name}}),
+			{{- end}}
+		),
+{{- end}}
+	)
+}
+{{- end}}

go-runtime/compile/build.go

@@ -53,12 +53,13 @@ type goVerb struct {
 }
 
 type mainModuleContext struct {
-	GoVersion    string
-	FTLVersion   string
-	Name         string
-	Verbs        []goVerb
-	Replacements []*modfile.Replace
-	SumTypes     []goSumType
+	GoVersion     string
+	FTLVersion    string
+	Name          string
+	Verbs         []goVerb
+	Replacements  []*modfile.Replace
+	SumTypes      []goSumType
+	LocalSumTypes []goSumType
 }
 
 type goSumType struct {
@@ -185,12 +186,13 @@ func Build(ctx context.Context, moduleDir string, sch *schema.Schema, filesTrans
 		goVerbs = append(goVerbs, goverb)
 	}
 	if err := internal.ScaffoldZip(buildTemplateFiles(), moduleDir, mainModuleContext{
-		GoVersion:    goModVersion,
-		FTLVersion:   ftlVersion,
-		Name:         result.Module.Name,
-		Verbs:        goVerbs,
-		Replacements: replacements,
-		SumTypes:     getSumTypes(result.Module, sch, result.NativeNames),
+		GoVersion:     goModVersion,
+		FTLVersion:    ftlVersion,
+		Name:          result.Module.Name,
+		Verbs:         goVerbs,
+		Replacements:  replacements,
+		SumTypes:      getSumTypes(result.Module, sch, result.NativeNames),
+		LocalSumTypes: getLocalSumTypes(result.Module),
 	}, scaffolder.Exclude("^go.mod$"), scaffolder.Functions(funcs)); err != nil {
 		return err
 	}
@@ -553,6 +555,29 @@ func writeSchemaErrors(config moduleconfig.ModuleConfig, errors []*schema.Error)
 	return os.WriteFile(config.Abs().Errors, elBytes, 0600)
 }
 
+func getLocalSumTypes(module *schema.Module) []goSumType {
+	sumTypes := make(map[string]goSumType)
+	for _, d := range module.Decls {
+		if e, ok := d.(*schema.Enum); ok && !e.IsValueEnum() {
+			variants := make([]goSumTypeVariant, 0, len(e.Variants))
+			for _, v := range e.Variants {
+				variants = append(variants, goSumTypeVariant{ //nolint:forcetypeassert
+					Name: v.Name,
+				})
+			}
+			sumTypes[e.Name] = goSumType{
+				Discriminator: e.Name,
+				Variants:      variants,
+			}
+		}
+	}
+	out := gomaps.Values(sumTypes)
+	slices.SortFunc(out, func(a, b goSumType) int {
+		return strings.Compare(a.Discriminator, b.Discriminator)
+	})
+	return out
+}
+
 func getSumTypes(module *schema.Module, sch *schema.Schema, nativeNames NativeNames) []goSumType {
 	sumTypes := make(map[string]goSumType)
 	for _, d := range module.Decls {

go-runtime/ftl/ftl_integration_test.go

@@ -49,3 +49,11 @@ func TestSchemaGenerate(t *testing.T) {
 		in.FileContains("build/schema-generate/test.txt", "olleh"),
 	)
 }
+
+func TestTypeRegistryUnitTest(t *testing.T) {
+	in.Run(t, "",
+		in.CopyModule("typeregistry"),
+		in.Deploy("typeregistry"),
+		in.ExecModuleTest("typeregistry"),
+	)
+}

go-runtime/ftl/testdata/go/typeregistry/ftl.toml

@@ -0,0 +1,2 @@
+module = "typeregistry"
+language = "go"

go-runtime/ftl/testdata/go/typeregistry/go.mod

@@ -0,0 +1,62 @@
+module ftl/typeregistry
+
+go 1.22.2
+
+toolchain go1.22.4
+
+require (
+	github.com/TBD54566975/ftl v1.1.5
+	github.com/alecthomas/assert/v2 v2.10.0
+)
+
+require (
+	connectrpc.com/connect v1.16.1 // indirect
+	connectrpc.com/grpcreflect v1.2.0 // indirect
+	connectrpc.com/otelconnect v0.7.0 // indirect
+	github.com/BurntSushi/toml v1.4.0 // indirect
+	github.com/TBD54566975/scaffolder v1.0.0 // indirect
+	github.com/alecthomas/atomic v0.1.0-alpha2 // indirect
+	github.com/alecthomas/concurrency v0.0.2 // indirect
+	github.com/alecthomas/participle/v2 v2.1.1 // indirect
+	github.com/alecthomas/repr v0.4.0 // indirect
+	github.com/alecthomas/types v0.16.0 // indirect
+	github.com/alessio/shellescape v1.4.2 // indirect
+	github.com/aws/aws-sdk-go-v2 v1.30.1 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/configsources v1.3.13 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.6.13 // indirect
+	github.com/aws/aws-sdk-go-v2/service/secretsmanager v1.32.1 // indirect
+	github.com/aws/smithy-go v1.20.3 // indirect
+	github.com/benbjohnson/clock v1.3.5 // indirect
+	github.com/danieljoos/wincred v1.2.0 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/hexops/gotextdiff v1.0.3 // indirect
+	github.com/jackc/pgerrcode v0.0.0-20240316143900-6e2875d9b438 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a // indirect
+	github.com/jackc/pgx/v5 v5.6.0 // indirect
+	github.com/jackc/puddle/v2 v2.2.1 // indirect
+	github.com/jpillora/backoff v1.0.0 // indirect
+	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/multiformats/go-base36 v0.2.0 // indirect
+	github.com/puzpuzpuz/xsync/v3 v3.2.0 // indirect
+	github.com/swaggest/jsonschema-go v0.3.72 // indirect
+	github.com/swaggest/refl v1.3.0 // indirect
+	github.com/zalando/go-keyring v0.2.5 // indirect
+	go.opentelemetry.io/otel v1.27.0 // indirect
+	go.opentelemetry.io/otel/metric v1.27.0 // indirect
+	go.opentelemetry.io/otel/trace v1.27.0 // indirect
+	golang.org/x/crypto v0.24.0 // indirect
+	golang.org/x/exp v0.0.0-20240604190554-fc45aab8b7f8 // indirect
+	golang.org/x/mod v0.18.0 // indirect
+	golang.org/x/net v0.26.0 // indirect
+	golang.org/x/sync v0.7.0 // indirect
+	golang.org/x/sys v0.21.0 // indirect
+	golang.org/x/text v0.16.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
+)
+
+replace github.com/TBD54566975/ftl => ../../../../..